linking error on mac

Hi,

One of the (very few) user of pfff, a code visualizer using lablgtk and cairo have issues compiling
lablgtk on his mac. 


make all -C external/ocamlgtk && make gui       -C commons 
make -C src all
ocamlmktop  -thread  -o lablgtktop unix.cma threads.cma  \
	   -I . lablgtk.cma gtkThread.cmo
File "_none_", line 1, characters 0-1:
Error: Error on dynamically loaded library: ./dlllablgtk2.so: dlopen(./dlllablgtk2.so, 138): Symbol not found: _gtk_major_version
 Referenced from: /Users/brbrooks/dev/pfff/external/ocamlgtk/src/dlllablgtk2.so
 Expected in: flat namespace
in /Users/brbrooks/dev/pfff/external/ocamlgtk/src/dlllablgtk2.so

Does it ring a bell to anyone ?

More information here:
https://github.com/facebook/pfff/issues#issue/2/comment/605609